The present invention relates to the use of steam misting in the production of polyamide filaments, especially for rectangular spinning nozzles in accordance with the bottom loading concept and a spinning system equipped therewith.
In the spinning of polyamides, especially for polyamide 6 (nylon 6), during the discharge of the filaments from the spinning nozzles monomers and oligomers in the form of unpleasant smoke clouds are produced which can be released in an uncontrolled manner into the surroundings. In order to prevent this, these emissions can be evacuated via suction nozzles which must be provided as close as possible to the spinneret outlets. The functions and the shapes of such suction nozzles have been made known in DE 198 36 682.5. From DE 198 30 453.6 it is known, further, that superheated steam which serves to moisten the polyamide filaments and to support the suction effect, can simultaneously increase the wiping interval time for the spinning nozzle when blown directly thereagainst.
Conventional devices which serve for the aforedescribed purposes are damaged however during the cleaning or replacement of the nozzles. Thus it has been, for example, proposed at one time to provide the conventional nozzle misting so that the steam is blown onto the longitudinal side of a rectangular nozzle stack centrally against the side wall of the relevant nozzle stack so that it then flows in the gap between the nozzle stack and the nozzle shaft in the spinning beam downwardly and is rerouted by a baffle plate more or less uniformly in the direction of the spinning plate. This device is, apart from the insufficiency of the moisturization produced, not usable for rectangular nozzle stacks in accordance with the bottom loading concept, is effective even to a lesser extent than is the solution for round spinning nozzles from the application DE 198 30 453.6 which differs based upon the after-heater which is directly following and also is not practical.
Thus it is the object to provide a reliable apparatus, which is service-friendly and is easy to clean, for the steam moisturization of rectangular nozzles.
The advantage of the new steam misting resides in the good temperature control of the steam, whereby the steam feed is effected through a tube loop which passes through the heating chamber of the spinning beam so as to bring the steam up to the spinning temperature. Advantageously, the steam outlet bars are directly below the spinning beam and thus on the lower edges of the rectangular nozzle stack connected therewith, between the spinning beam and the after-heater. These steam outlet bars are equipped with a simple labyrinth for pressure equalization which can be fabricated especially inexpensively. The steam inlet is effected initially respectively centrally to the rectangular nozzle stack and into an upwardly open and relatively broad distribution chamber along the rectangular nozzle stack.
This vertical distribution chamber transitions into a horizontal and very narrow gap space which opens into the spinning chamber. As the steam enters into the latter, the steam is spread out and uniformly flows in the direction of the nozzles. This is so effective that a misting from the ends inwardly is superfluous.